ESTRO 2020 Abstract book

S262 ESTRO 2020

The Proton Overseas Program (POP) was launched in 2008 by the National Health Service (NHS) to deliver high energy Proton Beam Therapy (PBT) abroad to UK patients until this became available in the UK (in 2018). The NHS used a systematic evidence based and prioritised approach. More than 10 years since its inception, we report the long term outcomes on patient groups who have accessed this programme; results compare favourably with other studies (1). Material and Methods Between 2008 and 2018, 1352 patients with eligible indications, from 46 centres across the UK, were referred for consideration of PBT. A national expert panel, adhering to approved criteria, established the appropriateness of PBT in each case. All cases were of sufficient performance status to travel, were appropriately staged and received treatment in experienced PBT centres. 1264 patients were approved (93.5 % of the referrals), 1096 (86.7%) were treated in North America and 168 (13.3%) were treated in Europe. Patient, tumour, treatment and follow-up data were collated in a centralised database. A Proton Clinical Outcomes Unit (PCOU) has been established to monitor this patient cohort as well as standardise and improve prospective outcome data collection for UK PBT patients going forward. Systematic follow-up data was available for 979 patients (77.1% of those approved for PBT). Mirroring the National Institute for Health and Care Excellence’s (NICE) definition of children, and Teenagers and Young adults (TYA), analysis has been conducted on the subgroups ≤25 vs >25 years old (y). Patients, disease and treatment characteristics are listed in Table 1. Results After a median follow-up of 34 months (range 6-123), the Local Control (LC) rate for the whole cohort is 85.3%; by age (≤25 y vs >25 y) LC rates are 87% for the younger group vs 78.8% for the older group. For tumours of the central nervous system (CNS), the LC rate is 84.1% (86.2% ≤ 25 y vs 79.2% > 25 y). For tumours outside the CNS the LC rate is 87.3% (88.1% in ≤ 25 y vs 75% in > 25 y). Further analysis on the major histological subgroups is listed in Table 1. The data show that LC is highest for craniopharyngioma (97.7%) in the CNS subgroup and for Ewing’s sarcoma (88.2%) in the body subgroup. Figure 1 illustrates the Kaplan-Meier survival estimates (95% Confidence Intervals) for the main groups. Conclusion The outcome of patients treated through the POP compares favourably with that reported in the literature (1). The POP has facilitated equitable access to PBT abroad for patients with complex needs from across the UK without disadvantaging patient outcome. The PCOU continues to collect data from these patients, as well as from patients who have been treated at the now established PBT service in UK. This prospective data registry will, over time, inform us further of the outcomes of patients treated with PBT to improve patient care. 1.Indelicato, DJ, et al Pediatr Blood Cancer . 2017; 64:12. OC-0442 Modelling and external validation of late side effects of brain tumours following proton therapy A. Dutz 1,2,3 , L. Agolli 1,4 , R. Bütof 1,4,5 , A. Lühr 1,2,3 , B. Michael 1,2,3,4,5,6 , X. Vermeren 7 , D. Geismar 7,8,9 , N. Lamba 10 , E.F. Schapira 10 , M. Bussière 10 , J.E. Daly 10 , M.R. Bussière 10 , M. Krause 1,2,3,4,5 , B. Timmermann 7,8,9,11 , H.A. Shih 10 , S. Löck 1,3,4,5 1 OncoRay - Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus- Technische Universität Dresden- Helmholtz- Zentrum Dresden - Rossendorf, Dresden, Germany ;

2 Helmholtz-Zentrum Dresden - Rossendorf, Institute of Radiooncology – OncoRay, Dresden, Germany ; 3 German Cancer Consortium DKTK, partner site Dresden- and German Cancer Research Center DKFZ, Heidelberg, Germany ; 4 Department of Radiotherapy and Radiation Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus- Technische Universität Dresden, Dresden, Germany ; 5 National Center for Tumor Diseases NCT, partner site Dresden, Dresden, Germany ; 6 German Cancer Research Center, Deutsches Krebsforschungszentrum DKFZ, Heidelberg, Germany ; 7 West German Proton Therapy Center Essen WPE, University Hospital Essen, Essen, Germany ; 8 Clinic for Particle Therapy, University Hospital Essen, Essen, Germany ; 9 West German Cancer Center WTZ, University Hospital Essen, Essen, Germany ; 10 Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, USA ; 11 German Cancer Consortium DKTK, partner site Essen, Essen, Germany Purpose or Objective To investigate late physician-rated side effects and their association with dosimetric parameters of various organs at risk (OARs) as well as clinical cofactors in adult brain tumour patients following proton beam therapy (PBT). Material and Methods Adult patients with brain tumours who underwent PBT at three different institutes were included in this study (N1=57, N2=47, N3=63). The radiation-induced side effects alopecia, fatigue, headache, memory impairment, hearing impairment, optic nerve disorder, dry eye and seizure (CTCAE v4.0) at 12 and 24 months after PBT were investigated. Side effects with sufficiently high incidence were dichotomised and correlated to different dose- volume histogram (DVH) parameters of associated OARs, such as skin, remaining brain, brainstem, cerebellum, hippocampi and cochlea. Clinical parameters comprised age, gender, tumour volume, prescribed dose, concomitant chemotherapy, resection of the tumour, diagnosis and WHO grading. Normal tissue complication probability (NTCP) models were developed on a combined cohort from two institutes (N=104) using logistic regression. The area under the receiver operating characteristic curve (AUC) was used to assess the prognostic ability in external validation on the remaining In all cohorts, low toxicity rates were observed at 12 and 24 months after PBT. Most common side effects were fatigue (grade≥1: 32%/27%, grade≥2: 14%/6% at 12/24 months), alopecia (grade≥1: 30%/22%) and mild memory impairment (grade≥1: 23% at 24 months). Mild headache and hearing impairment (grade≥1) occurred in 20%/19% and 8%/9% of all patients at 12/24 months, respectively. Logistic regression revealed significant correlations between the incidence of alopecia grade≥1 at both times and high dose regions of the skin (D2%, p<0.001, figure A). Hearing impairment grade≥1 at 24 months after PBT was associated with the median dose to the ipsilateral cochlea. For both endpoints, the developed NTCP models were successfully validated (AUC≥0.78, figure B). cohort. Results